1. Field of the Invention
The invention relates in general to padding materials and more specifically to gelatinous viscoelastic padding materials impregnated onto an adhesive-backed fabric for fixation to human tissue.
2. Description of the Prior Art
Historically, articles of many different compositions have been utilized in medicine and podiatry to protect and pad human tissue. Most of the articles have been made of soft, compressible materials such as lamb's wool, felt, and foam rubber. One example of such padding is an adhesive-backed felt fabric known by the generic name moleskin. In order to use moleskin in an area of limited space such as inside the narrow confines of a shoe, the felt layer must be relatively thin. Using a thin layer of felt limits the moleskin's ability to protect human tissue from pressure and shear forces generated by walking. Another commonly-employed padding material is foam rubber. Again, in the narrow confines of a shoe a relatively thin layer of foam rubber must be employed or it will be compressed to the point where it becomes hard or "bottoms out" and loses its ability to distribute pressure around an uneven surface. Each material's ability to dissipate pressure and shear forces is diminished when it is used in thin layers.
In recent years, a new class of materials has been developed which shows great promise as padding. These materials are the soft, gelatinous viscoelastic polymers. Gelatinous viscoelastic polymers have the ability to distribute pressure around an uneven surface in a manner similar to hydraulic fluid in a brake or pump. Because of their elastic, resilient nature, viscoelastic materials have the ability to return to their original shape after removal of a deforming force. These characteristics of viscoelastic gels lead to superior results when they are used as padding. For example, when a viscoelastic pad is placed between a bony prominence of a bunion and the relatively unyielding material of a shoe, the pad conforms to the shape of the bony prominence and thus distributes pressure and shear forces generated by the shoe in a manner far superior to conventional materials. When the deforming forces are removed, i.e., the shoe is removed, the viscoelastic gel returns to its original conformation.
Since most gelatinous viscoelastic polymers will not bond directly to an adhesive because they contain plasticizing oils or because of the intrinsic nature of the polymer itself, it has not been possible to affix pads fashioned from these polymers directly to another surface by means of a pressure-sensitive adhesive. Heretofore, these pads were simply laid on the structure to be protected and held in place by body weight, gravity, or opposing body surfaces. In some cases, elaborate taping, bandaging, or enclosure techniques were employed. The present invention solves this problem by impregnating the gelatinous viscoelastic padding onto a layer of fabric and coating a portiton of the fabric with a pressure-sensitive adhesive.